Answer
$-1$
Work Step by Step
Using $i^2=-1$ and the laws of exponents, the given expression, $
(-i)^{6}
,$ is equivalent to
\begin{array}{l}\require{cancel}
i^6
\\\\=
\left( i^2 \right)^{3}
\\\\=
\left( -1 \right)^{3}
\\\\=
-1
\end{array}